The general preparation of silver nanowires (10-200 aspect ratio) from silver ions is known. See, for example, Y. Xia, Y. Xiong, B. Lim, S. E. Skrabalak, Angew. Chem. Int. Ed. 2009, 48, 60, and J. Jiu, K. Murai, D. Kim, K. Kim, K. Suganuma, Mat. Chem. & Phys., 2009, 114, 333, both of which are hereby incorporated by reference in their entirety. Such preparation methods have typically been carried out in the presence of metal chlorides, such as chlorides of iron (II), iron (III), copper (I), copper (III), and the like. The nanowires produced in the presence of metal chlorides are often too thick for many commercial applications.
When iron or copper are used, they are typically provided as the metal halide salts FeCl2 or CuCl2. See, for example, B. Wiley et al., Nano Letters, 2004, 4, 1733-1739 and K. E. Korte et al., J. Mats. Chem., 2008, 18, 437. Other metal halide salts have been used in nanowire synthesis. See, for example, J. Jiu, K. Murai, D. Kim, K. Kim, K. Suganuma, Mat. Chem. & Phys., 2009, 114, 333, which refers to NaCl, CoCl2, CuCl2, NiCl2 and ZnCl2, and S. Nandikonda, “Microwave Assisted Synthesis of Silver Nanorods,” M. S. Thesis, Auburn University, Auburn, Ala., USA, Aug. 9, 2010, which refers to NaCl, KCl, MgCl2, CaCl2, MnCl2, CuCl2, and FeCl3. Japanese patent application publication 2009-155674 discloses SnCl4.
Use of KBr has been disclosed in, for example, D. Chen et al., J. Mater. Sci.: Mater. Electron., 2011, L. Hu et al., ACS Nano, 2010, 4(5), 2955-2963, C. Chen et al, Nanotechnology, 2006, 17, 3933. Use of NaBr has been disclosed in, for example, L. Zhou et al., Appl. Phys. Letters, 2009, 94, 153102.